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Subject: Re: [korgpolyex] Re: Poly 800 mk1 playing up (still very workable)

From: Sami Jumppanen <sami.jumppanen@...>
Date: 2014-04-04

Hi,
PSU milliamps = max current output. The more the safer for operation - the worse for short circuits ;).
PSU don't "push" current into Poly, it's the Poly that draws the current. In other words: it takes what it needs and the rest from the supply is just "not used".

Why only the 300mA PSU worked for you, Jill, is explained by some ∗other∗ factor than the milliamp rating. That's what I can place a bet on. What it is, I can only guess.

Some PSU's give poorly regulated (humming, unsteady) voltage that may drop below the required voltage level under load. These days the transformer PSU's are luckily replaced by switching-mode PSU's. You identify them by their light weight vs. higher current output. There is no big transformer with iron core inside. I don't know if there are switching-mode PSU's that cause unwanted high frequency noise for Poly. 

In the past I've also seen PSU's that give a lot more than the nominal volts. I don't know if that is a problem for a Poly, or that it could cause the depicted symptoms.

Just my 9 volts... :)

Sami "Some-E" Jumppanen



On Fri, Apr 4, 2014 at 11:36 AM, Jill Saphic <jill_saphic@...> wrote:
 

well then!
that sounds terrible, doesn't it.
Poly-800s dont seem sturdy, but they are put together by KORG
with being strapped on and played in mind, banging against your
legs and being picked up and put back down lots!
the sound from the lighting is usually shielding of some kind isn't in place.
The only thing I've seen make a Poly-800 lose it's internal memory is
power outage with no battery backup/dead batteries.
Even if it's just unplugged from the wall without batteries installed
or the ones in there are dead.
Did you make sure you got the right milliamps on your new PSU.
Thats really important, and don't believe that its not, especially on
a plastic economy synthesizer. did you see this on the net:
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
KORG POLY-800 PSU
Part/Model number:
KAC9500
center plug is 2,1 mm.
outer ring of PSU connector is "+" positive.
center tip of PSU connector is "-" negative.
 
 Power: DC- 9Volts-300ma miliamps)
"or" alkaline batteries (C cells x 6)
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
If you went over 300, thats a bit of a problem...
I waited for a couple of months to AC--> power mine on
and just used batteries untill I found the right one
with exactly 300 ma, I can imagine it going all wonky
if it had too hot a power supply.
But hey, just a thought! maybe it helps...
 
 
Last time I came here you where all very helpful and I found I just really needed a new PSU for my Poly 800 (got one now). Problem this time around is that I took my poly on a little trip and then it wouldn't turn on pre gig practice (I admit I didn't have a proper case for it) and it was making garbage sounds like just sounded like junk and there where some issues with lights etc.

I take it home and leave it a few days and then suddenly I can power it on again but the presets have all gone and now the headphone jack isn't responding to the volume pot (but still works). Volume pot also a bit crackly




--
Sami Jumppanen
http://netti.nic.fi/some-e